JP2000139089A - Ultrasonic motor and manufacture thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To achieve efficient and stable operation where performance does not change initially and at the same time even after a long drive by performing finishing machining to each sliding surface of a vibration body and a movable body by a smoothing means for making equivalent surface roughness and further using the same quality of materials. SOLUTION: In a vibration body 101, the shape is machined from a round-rod raw material A1 by an NC lathe and a sliding surface is also finished by cutting machining. In a friction material 104, the outer shape is formed by injection molding, the material 104 is glued and fixed to a movable body 103, and then the sliding surface is finished by cutting machining. In this manner, both sliding surfaces of the vibration body 101 and the friction material 104 are subjected to finish machining so that the equivalent surface roughness can be achieved by a smoothing means, thus improving performance and durability. Then, compound plastic with the same quality as that of the friction material 104 is glued to the sliding surface of the vibration body 101, and the sliding surface is subjected to finish machining so that the surface roughness being equivalent to that of the friction material 104 is achieved.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultrasonic motor for converting the expansion and contraction movement of a piezoelectric element into rotation and linear movement, and a method for manufacturing the same.

[0002]

2. Description of the Related Art FIG. 2 shows the structure of a conventional ultrasonic motor. The vibrating body 201 is fixed to the center shaft 208 fixed to the fixed base 209. A polarized piezoelectric element 202 is adhered to the lower surface of the vibrating body 201. The moving body 203 contacts the displacement magnifying mechanism 205 of the vibrating body 201 via a friction material (not shown). The moving body 203 has a central axis 208.
, And pressed against the vibrating body 201 by a pressure spring 207. When a plurality of high-frequency voltages having different phases are applied to the piezoelectric element 202, flexural vibration occurs in the vibrating body 201, and the pressed moving body 203 is rotated by a frictional force. Since such an ultrasonic motor is driven by friction, the state of the contact surface greatly affects the performance of the motor. Therefore, conventionally, the sliding surface of the vibrating body 201 and the sliding surface of the friction material are separately determined for the material by determining conditions,
Finishing of the surface was performed.

[0003]

However, even if the surface processing of the vibrating body or the sliding surface of the moving body or the material is individually determined as in the prior art, the other side is affected to a considerable extent during driving. The magnitude of the effect increases as the surface state and material properties differ. Therefore,
Initially, even if the performance is good, there is a problem that an unstable ultrasonic motor having inefficient efficiency such that the performance changes as the driving time increases is obtained.

[0004] Therefore, an object of the present invention is to solve the above-mentioned problems in the prior art, in which the performance is good even at the initial stage, and the performance does not change even if driven for a long time. To obtain a simple ultrasonic motor.

[0005]

In order to solve the above-mentioned problems, the present invention relates to an ultrasonic motor which frictionally drives a moving body by pressing a moving body against the vibrating body and generates a wave by the expansion and contraction of a piezoelectric element. Each sliding surface of the moving body is subjected to finish processing by smoothing means to achieve the same surface roughness, and by using the same material, an efficient and stable ultrasonic motor can be obtained. did.

When the ultrasonic motor is driven, the state of contact between the vibrating body and the sliding surface of the moving body is enlarged as shown in FIG. That is, a part of the displacement magnifying mechanism 305 is in contact with the friction material 304. Further, when viewed microscopically, the friction material 5 having a constant surface roughness as shown in FIG.
It is considered that the discontinuous surfaces of 04 and the vibrating body 501 are in non-uniform contact. In this case, the surface condition of the sliding surfaces of each other, that is, the surface roughness is extremely different, and if a material having a large surface roughness is used, the sliding surface is easily worn.

[0007] However, when the respective sliding surfaces of the vibrating body and the moving body are subjected to finishing by a smoothing means as in the present invention and the surface roughnesses of the two are made equal, the respective surface conditions are almost equal. In other words, even when viewed microscopically, a more uniform contact state can be obtained as shown in FIG. In addition, by making the material of each sliding surface the same, the manner of wear becomes equal, and the change in the surface condition is reduced.

[0008] From the above operation, the surface state is stabilized, and an ultrasonic motor having stable characteristics with high efficiency can be obtained.

[0009]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows the basic structure of an ultrasonic motor according to the present invention. An ultrasonic motor in which the diameter of the body 106 of the vibrating body 101 in which the structure of the present invention was actually implemented was 10 mm was manufactured. The material of the vibrating body 101 was Al, and the material of the friction material 104 was a composite plastic containing carbon fiber.

The shape of the vibrating body 101 was processed from an Al round bar raw material by an NC lathe, and the sliding surface was finished by cutting.
The outer shape of the friction material 104 is formed by injection molding.
After bonding and fixing to No. 03, the sliding surface was finished by cutting. The ultrasonic motor was driven to investigate the performance and durability. The measurement results of the efficiency indicating the performance of the ultrasonic motor were as shown in FIG. 6 (a), and the durability was as shown in FIG. 7 (a).

Next, the sliding surface of the friction material 104 of the ultrasonic motor was wrapped with 1500 ° abrasive grains, and its performance and durability were examined. The efficiency was shown in FIG. 6 (b). The result was as shown in FIG. 7 (b). Further, the sliding surface of the vibrating body 101 is
As in the case of Example No. 04, lapping was carried out with 1500 ° abrasive grains, and the efficiency and durability were examined. The results are as shown in FIG. 6 (c) for the efficiency and FIG. 7 (c) for the durability.

Comparing the above three working methods, the best one is obtained when the sliding surfaces of both the vibrating body 101 and the friction material 104 are wrapped in the same manner.
That is, as shown in FIG. 6, the efficiency of the ultrasonic motor is
The one obtained by lapping both the sliding surface of the friction material and the sliding surface of the vibrating body is the highest (FIG. 6 (c)), and the second one is obtained by lapping only the friction material (FIG. 6 (b)). ).

Further, as shown in FIG. 7, the durability of the ultrasonic motor is most stable when both the sliding surface of the friction material and the sliding surface of the vibrating body are wrapped (FIG. 7). FIG. (C)), and the next is the result of lapping only the friction material (FIG. (B)). And as the smoothing means of the present invention, not only lapping but also grinding, honing,
Buffing, chemical polishing, electrolytic polishing, barrel processing, shot peening, and the like can be applied.

When the sliding surfaces of both the vibrating body and the friction material are finished by the smoothing means so as to have the same surface roughness, the performance and durability are improved. In another embodiment, the outer shape of the vibrating body is formed by die-casting using a motor having an outer diameter of about 30 mm, and the sliding surface is ground, and the friction material is outsert-molded on the moving body and ground under the same conditions. Finished. The performance and durability of the ultrasonic motor according to the present invention were also improved by the experimental results.

Next, a composite plastic of the same material as the friction material was adhered to the sliding surface of the vibrator, and the sliding surface was finished to have the same surface roughness as the friction material. When the performance and durability were examined by combining the vibrating body with the preceding moving body, the durability was improved as compared with the case where the vibrating body was Al.

[0016]

As described above, according to the present invention, the smoothing means is used to finish the sliding surfaces of the vibrating body and the moving body so as to have the same surface roughness, and to use the same material. Accordingly, a uniform contact state can be obtained both initially and over time, and there is an effect that an ultrasonic motor having high efficiency and excellent durability can be obtained.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a basic structure of an ultrasonic motor according to the present invention.

FIG. 2 is a perspective view showing a basic structure of an ultrasonic motor.

FIG. 3 is a sectional view showing a contact state of the ultrasonic motor according to the present invention.

FIG. 4 is a sectional view when the contact state of the ultrasonic motor according to the present invention is viewed microscopically.

FIG. 5 is a cross-sectional view when the contact state of a conventional ultrasonic motor is viewed microscopically.

FIG. 6 is a diagram comparing the efficiency of an ultrasonic motor according to the present invention with that of a conventional ultrasonic motor.

FIG. 7 is a diagram comparing the durability of an ultrasonic motor according to the present invention and a conventional ultrasonic motor.

[Explanation of symbols]

 101, 201, 301, 401, 501 Vibrating body 102, 202, 302 Piezoelectric element 103, 203, 303 Moving body 104, 204, 304, 404, 504 Friction material 105, 205, 305 Displacement magnifying mechanism 106, 206, 306 Body part 107, 207 Pressing spring 108, 208 Center axis 109, 209 Fixed base

Claims (3)

[Claims] 1. An ultrasonic motor comprising: a vibrating body having a piezoelectric element; and a moving body which is pressed against the vibrating body and is frictionally driven by the expansion and contraction of the piezoelectric element, wherein a sliding surface of the vibrating body; An ultrasonic motor, wherein a sliding surface of a moving body is subjected to finishing by the same smoothing means. 2. The ultrasonic motor according to claim 1, wherein the sliding surface of the vibrating body is finished by cutting, and the sliding surface of the moving body is finished by lapping. 3. The material according to claim 1, wherein one of the materials of the sliding surfaces of the vibrating body and the moving body is an aluminum alloy, and the other is a composite plastic material containing carbon fiber. Item 3. An ultrasonic motor according to item 2.